Hydraulic control systems typically convert rotating mechanical power into hydraulic fluid power. Hydraulic control systems typically include hydraulic pumps that convert mechanical energy (e.g., torque from a power source such as an electric motor or an engine). One common type of hydraulic pump is an axial piston pump. Axial-piston pumps are often used to power the hydraulic systems of jet aircrafts. An axial-piston pump is a positive displacement pump having a rotating group that includes a number of piston-shoe assemblies arranged in a circular array, powered around a drive shaft, within a piston block. The rotating group can be enclosed within a pump casing containing hydraulic fluid. The pump can be cooled by providing a controlled flow of hydraulic fluid through the pump case. Typically, hydraulic flow into the pump case can be provided by normal leakage from the rotating group of the pump and other leakage sources. Pump cases typically also have case drain ports for allowed hydraulic fluid to exit the pump cases and flow to a system reservoir.